This invention relates to a method of determining whether or not a region in a given picture is within a closed boundary.
It is very important to determine whether or not a picture cell of a given picture is within a closed boundary, in order to for example, compute the area of the closed region and on the same line. According to one of the conventional methods of determining or extracting the picture cells within the closed region the picture cells located on each scanning line and aligned between two boundary points are filled one by one with reference to connectivity of the picture cells on the boundary. A disclosure of such a prior art is found in, for example, A. Rosenfeld, "Picture Processing by Computer" Academic Press [1969].
Such prior art requires a considerable memory capacity for storing the lists indicating the connectivity of the boundary points, and also requires complicated programming as well as a relatively long processing time. More specifically, according to the prior art in question, the stored picture information is first read out line by line, and second, as each line is read out, the boundary points of the read-out line are searched with reference to the connectivity list. Then the picture cells between the detected boundary points are filled. Therefore requiring the large capacity memory and complicated programming etc, as previously mentioned.
Furthermore according to the prior art, it is impossible to analyze an island, viz., a region which is enclosed by a closed boundary and which has no connectivity therewith.